Evolution of reproductive strategies in plants Flashcards
What kind of organisms are plants?
Sessile.
What environment were plants originally in?
Aquatic areas.
What did colonisation of land require?
Considerable adaptations - support, avoiding drying out, obtaining water and gases, reproduction, resisting predation.
What were the four key points in evolutionary development?
Land plants, vascular plants, seed plants, flowering plants.
What two seres of things happened over time?
Explosions of diversity and catastrophic extinctions.
What kind of plants existed initially?
Vascular plants, lycophytes and pteridophytes.
What came after vascular plants?
Seed-bearing plants (gymnosperms).
What came after seed-bearing plants?
Flowering plants (angiosperms).
What is an anthophyte?
Any flowering plant.
What is the Anthopyte hypothesis (angiosperm evolution)?
Bennettitalles suggested to be link between Gnetophytes and Angiosperms, based on early molecular data.
What did evolution of flowers lead to?
Major evolutionary event leading to massive diversification of species.
What is one plant considered to be the oldest angiosperm so far?
Montsechia Vidalii (debated) or Archaefrustus Sinensis.
What are the key terms for flowering plants?
Sepal, petals, stamen, carpel, tepal - four whorls.
What is the Sepal?
Calyx, outer part of flower (leafy green structures).
What are the petals?
Corolla, main bulk, numerous and individual, may be fused.
What is the stamen?
Androecium, produces pollen, consists of anther and filament.
What is the Carpel?
Gynoecium, female structure, composed of ovary, style and stigma.
What is the Tepal?
Flower/ sepal hybrid structure.
What is Amborella trichopoda?
Small plant native to rainforest of New Caledonia - South Pacific.
What is significance of A.trichopoda?
Related to all flowering plants, oldest confirmed branch of angiosperm family tree.
What structural difference did early flowers most likely have?
Tepals rather than sepals and petals.
How was the predicted structure of the first flower developed?
Analysis of genetics of flowering groups, extrapolated common features back to identify common likely features.
What is the probably structure of first flower?
Tepals and stamens, layered whorls of 3, 11 or more tepals and stamens, male and female structures, ~1cm diameter.
Did flowers become more or less complex over time?
Less complex, more aligned to common format.
How has the floral structures changed over time?
Simplified, flattened from complex spiral arrangements to simpler symmetrical arrangements.
What did later development divide tepals into?
Petals and sepals.
When did petal fusion occur?
Later in evolutionary lineages - specialised flowers, specific functions to encourage pollenators.
What happened to symmetry of flowers over time?
Radial symmetry became less common compared to bilateral symmetry.
What happened to the Carpel over time?
Tended to be inferior to flower rather than superior - generally primitive in early angiosperms.
What developed over time with insect evolution?
Nectaries.
What did early/simple plants use for survival and reproduction?
Spores (2n) and water borne gametes (n).
What is the problem of early plant reproduction traits?
Require water and humid environments, only work in close proximity.
What are pollen grains?
Male gametophytes.
Characteristics of pollen grains?
Carried by wind, water or pollinator, protected from desiccation, not dependant on water, grow pollen tube to reach female gamete.
What does sperm in Cycads and Gingko still possess?
Flagella to swim down pollen tube to female gamete.
How has pollen evolved?
Complex and specialised, resistant to desiccation, light and transferable, distinct 3D shape.
How has dispersal of pollen changed to overcome major challenge?
Initially wind dispersal, eventually animal pollinators used.
Give advantages of wind pollination.
Happen at any time, not reliant on another spp, long distances, continuous.
Give disadvantages of wind pollination.
Slim chance finding target, huge amounts required, no direction, close range effectiveness, sticky stigma needed.
Give advantages of pollenators.
Efficient, high volumes, large distances, less required, more certainty.
Give disadvantages of pollenators.
Costly to produce floral structures, development of complex structures, species loyalty, seasonal reliance, resource vs benefit.
Has co-evolution between plants and pollenators been shown?
Yes, strong suggestions.
Explain the co-evolution of flowers and insects.
Coevolved with particular pollinators, uniquely structured flowers, attractive features to particular pollinator, shaped to cover with pollen.
What is the plant vs pollinator arms race?
Plant wants to be promiscuous but frugal, pollinator wants to be well-fed and lazy.
Explain the plants side of the arm race.
Lots of pollen spread, low energy waste on encouraging pollinators, maximum transfer, make pollinator work.
Explain the pollinators side of the arms race.
Lots of food for minimal effort, maximal amount of nectar, minimal energy expenditure.
What do seeds contain?
Diploid embryo that will germinate into sporophyte, storage tissue, protective coat, hardened tissue to prevent desiccation.
What is urbanisation in plant evolution?
Changing conditions and ecosystems require adaption to changes in plant distribution and pollinator availability.
What is climate in plant evolution?
Warming environment will need to lead to change in local structures, flowering times, species re-adaptation.
What is dispersal by human causing hybrids in plant evolution?
Subspecies of plants hybridise easily, movements of plants and seeds around the world increases chances of hybrids being formed.
